Function called in `load' to load an Emacs Lisp source file.
The value should be a function for doing code conversion before
reading a source file. It can also be nil, in which case loading is
done without any code conversion.
If the value is a function, it is called with four arguments,
FULLNAME, FILE, NOERROR, NOMESSAGE. FULLNAME is the absolute name of
the file to load, FILE is the non-absolute name (for messages etc.),
and NOERROR and NOMESSAGE are the corresponding arguments passed to
`load'. The function should return t if the file was loaded.